/Engine/Source/Runtime/GeometryCore/Public/PlaneTypes.h
N is specified, c = Dot(N,P) where P is a point on the plane.
TPlane3 ( const [UE::Math::TVector](API\Runtime\Core\Math\TVector)< RealType > & Normal, const [UE::Math::TVector](API\Runtime\Core\Math\TVector)< RealType > & Point )